The first decan of Aries spans degrees 0 through 9 of the sign. Each decan has a planetary ruler and this decan is ruled by Mars. Since Aries itself is ruled by Mars there is heightened signature of martial energy in this decan. Mars is the god of war, action, aggression. Mars stabs. Mars cuts away. Mars servers. Mars penetrates.
T. Susan Chang refers to this decan as the Lord of Dominion. Looking at the 2 of Wands, the tarot card correlated to this decan, we see a figure holding a globe and looking over the world under his command. There is an energy of desire with this decan, but at what expense? At whose expense? The figure dreams of conquering the whole world. His ambition is limitless.
Kira Ryberg (@kirastrology), in her book 36 Decans, highlights the initiatory energy of this first decan of Aries. This decan begins where the spring equinox occurs, when the days become longer than the nights, when the earth warms and plants can grow. This decan can speak as much to the work of cultivation as it does to domination. What desire is germinating? What seedling is pushing headlong through the darkness of soil to break free into the the light of the Sun?
Kira also notes that the martial energy of this decan can be expressed as protection and advocacy, not only destruction or oppression.
Thinking about natal placements or planets transiting this slice of the zodiac, I wonder how courage, bravery, thirst for power, the drive to protect, or will to succeed color the meaning of that astrology.